Would be interested to know if anyone knows of any possible contenders for the fastest rpm stirling/hot air engine in the world?. This is not an official recognition or prize winning ceremony so feel free to submit any legends you heard at the bar as well as some genuine examples of very fast engines.

I bet mr ross will be disappointed to hear that my Mk1 combobulator achieved a free speed of 4701RPM. I just wish I had made a video before it was stolen by a dozen masked Chinese cat burglars who were obviously stealing it for the Chinese military.

Wellington, with a bit of work you could get nearer to 4000 rpm, first change the aluminium displacer for a stainless steel one, make a burner that gets the hotcap evenly red, fit free running bearings on main and con rod big ends. Improve the cooling, either a fan, or change to water cooling. Nice motor, don't touch it, it's ok as is.A mate has one similar that he got in USA, years ago he was building and selling solar hot water systems, and used the motor to demonstrate the power of the sun. I think his will do 3000 + rpm.Ian S C